According to the LA City standards, which gas is most commonly used for GMAW?

In the context of Gas Metal Arc Welding (GMAW), commonly referred to as MIG welding, the most widely used shielding gas is carbon dioxide (CO2). This gas is favored for several reasons. It provides a good balance of penetration and heat input, which is essential for creating strong welds in various types of steel. CO2 is also cost-effective and readily available, making it a practical choice for many welding applications.

When using CO2 with GMAW, it can produce a sound weld with good bead appearance and is often used for welding thicker materials. While other gases such as argon or a mixture of argon and CO2 can also be utilized, particularly for specific applications or material types, CO2 remains the most common gas in many industrial settings, particularly in non-automotive applications. In Los Angeles City standards and practices, adherence to GMAW with CO2 aligns with industry norms and expectations, making it a standout choice for structural welding.

Given these factors, CO2's prominence in the welding landscape explains why it is recognized as the most commonly used gas in GMAW, in accordance with LA City standards.